Gonorrhea is becoming untreatable. This common and potentially serious sexually transmitted disease was once easily cured. But now, of the 50 antibiotics once used to treat the infection, only one drug works — and just barely.

Bacterial resistance to antibiotics isn’t just a problem in hospitals anymore. Resistant bacteria are hitting the streets — and we lack the tools to deal with the growing crisis.

The bacteria that cause gonorrhea have grown resistant to all other antibiotics; ceftriaxone, the sole survivor, is hanging on for dear life. To preserve its efficacy, the Centers for Disease Control and Prevention has come up with new guidelines for treating the infection.

Rather than being handed pills, patients must now get an injection of ceftriaxone accompanied by a second oral antibiotic. This will slow the progression of bacterial resistance to the drug, but it won’t stop it.

There is no way to win the resistance war against bacteria. Over time, even with the most prudent use of antibiotics, resistance is all but certain. The best we can do is to “keep up” with the germs by discovering new antibiotics that will kill the resistant strains.

Yet the federal Food and Drug Administration effectively discourages research into new antibiotics.

During the late 1990s, the FDA suddenly decided to require “better” statistical power for clinical trials of antibiotics by requiring companiesto enroll about twice as many subjects, making trials much lengthier and prohibitively expensive — yet no more medically relevant.

Dr. David Shlaes, the former vice president of infectious disease research at Wyeth, found himself squarely in the middle of this battle in 1999. After countless meetings with the FDA over a three-year period, he finally convinced the agency to postpone its new clinical requirements so that Wyeth could continue the development of its antibiotic Tigacyl, which would have otherwise been dropped.

Back then, Shlaes predicted that if the FDA didn’t reverse course, it would bring antibiotic research in the US to a screeching halt. He was right — research died.

One by one, drug companies pulled the plug on their antibiotic programs — including, ultimately, Wyeth.

We’re now starting to pay dearly for this. Only two new antibiotics have been approved in the United States since 2007, compared to an average of four a year in the 1980s. Only four of the 12 major drug companies remain in this area of research at all.

The absence of robust antibiotic discovery programs threatens to profoundly alter the practice of infectious disease medicine, to some extent binging us back to 1940, before antibiotics were available.

We are now thisclose to having no drugs to treat gonorrhea — an infection that 300,000 Americans a year contract even when we have antibiotics to control it.

The nation is looking at a very scary public-health problem.

Warns Shlaes, “This is a train wreck already in motion. As other resistant bacteria continue to work their way through the general public, we will soon be seeing more cases of pneumonia and urinary tract infections that will be impossible to treat.”

There is at least a glimmer of hope. At a lecture in May, Dr. Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, said that the agency will soon “reboot its approach to antibacterial development.”

Shlaes hopes it is not too late: “If the FDA does not reboot soon, Americans will be left to fend for themselves with increasing numbers of untreatable infections. This will be very bad indeed.”

Josh Bloom is the director of chemical andpharmaceutical sciences at the American Council on Science and Health.